While looking up the old Copernican model for orbits, I encountered the following image (courtesy Wikipedia):
This seems... weird. Not only would it be an odd thing to come up with or express in mathematics, it also doesn't make much sense intuitively. Even if they weren't using rigorous mathematics to develop the model... why would they ever consider this a reasonable orbit?
I understand that not much about orbiting bodies was known at the time, but it still leads me to wonder why they would consider this viable. In particular:
- In such a model, wouldn't Mars change size in the sky?
- Wouldn't Mars tend to delay at a particular point in the sky for a measurable length of time?
Why would these things not be immediately obviously wrong to anyone who could observe these bodies? Of note, I'm assuming they had some method of observing the location of Mars, since the model includes its existence.